var age = 19
var b = 2

console.log(age-b)
console.log(age*b)
console.log(age+b)
console.log(age/b)
console.log(age%b) // 1


// 当加号的其中一侧为字符串，则为字符串拼接
console.log('我今年'+ '18' + '岁了')
console.log('我今年'+ age + '岁了')

// 往字符串添加变量, '+变量+'